Advance in Functional Restoration of Injured Nerve with Low Level Laser and its Utilization in the Dental and Maxillofacial Region.

The inferior alveolar nerve and facial nerve are the two most important nerves in the dental and maxillofacial region. The injury to them is one of the major postoperative complications after alveolar surgery and orthognathic surgery. However, recovering the nerve function after injury takes a long time and the recovery effect tends to be unsatisfactory. In recent years, an intensively investigated technique, low level laser which has been applying in assisting the recovery of nerve function, has been gradually proved to be effective in clinically treating postoperative nerve injury. In this article we review in terms of the mechanisms involved in low level laser-assisted functional restoration of nerve injury and its clinical application in the recovery of nerve function in the dental and maxillofacial area as well.

Establishment of tooth blood supply and innervation is developmentally regulated and takes place through differential patterning processes.

Teeth are richly supported by blood vessels and peripheral nerves. The aim of this study was to describe in detail the developmental time-course and localization of blood vessels during early tooth formation and to compare that to innervation, as well as to address the putative role of vascular endothelial growth factor (VEGF), which is an essential regulator of vasculature development, in this process. The localization of blood vessels and neurites was compared using double immunofluorescence staining on sections at consecutive stages of the embryonic (E) and postnatal (PN) mandibular first molar tooth germ (E11-PN7). Cellular mRNA expression domains of VEGF and its signaling receptor VEGFR2 were studied using sectional radioactive in situ hybridization. Expression of VEGF mRNA and the encoded protein were studied by RT-PCR and western blot analysis, respectively, in the cap and early bell stage tooth germs, respectively. VEGFR2 was immunolocalized on tooth tissue sections. Smooth muscle cells were investigated by anti-alpha smooth muscle actin (αSMA) antibodies. VEGF showed developmentally regulated epithelial and mesenchymal mRNA expression domains including the enamel knot signaling centers that correlated with the growth and navigation of the blood vessels expressing Vegfr2 and VEGFR2 to the dental papilla and enamel organ. Developing blood vessels were present in the jaw mesenchyme including the presumptive dental mesenchyme before the appearance of the epithelial dental placode and dental neurites. Similarly, formation of a blood vessel plexus around the bud stage tooth germ and ingrowth of vessels into dental papilla at E14 preceded ingrowth of neurites. Subsequently, pioneer blood vessels in the dental papilla started to receive smooth muscle coverage at the early embryonic bell stage. Establishment and patterning of the blood vessels and nerves during tooth formation are developmentally regulated, stepwise processes that likely involve differential patterning mechanisms. Development of tooth vascular supply is proposed to be regulated by local, tooth-specific regulation by epithelial-mesenchymal tissue interactions and involving tooth target expressed VEGF signaling. Further investigations on tooth vascular development by local VEGF signaling, as well as how tooth innervation and development of blood vessels are integrated with advancing tooth organ formation by local signaling mechanisms, are warranted.

Bone Marrow Stromal Cells Promote Innervation of Bioengineered Teeth.

Transplantation of bone marrow mesenchymal stem cells (BMDCs) into a denervated side of the spinal cord was reported to be a useful option for axonal regeneration. The innervation of teeth is essential for their function and protection but does not occur spontaneously after injury. Cultured reassociations between dissociated embryonic dental mesenchymal and epithelial cells and implantation lead to a vascularized tooth organ regeneration. However, when reassociations were coimplanted with a trigeminal ganglion (TG), innervation did not occur. On the other hand, reassociations between mixed embryonic dental mesenchymal cells and bone marrow-derived cells isolated from green fluorescent protein (GFP) transgenic mice (BMDCs-GFP) (50/50) with an intact and competent dental epithelium (ED14) were innervated. In the present study, we verified the stemness of isolated BMDCs, confirmed their potential role in the innervation of bioengineered teeth, and analyzed the mechanisms by which this innervation can occur. For that purpose, reassociations between mixed embryonic dental mesenchymal cells and BMDCs-GFP with an intact and competent dental epithelium were cultured and coimplanted subcutaneously with a TG for 2 wk in ICR mice. Axons entered the dental pulp and reached the odontoblast layer. BMDCs-GFP were detected at the base of the tooth, with some being present in the pulp associated with the axons. Thus, while having a very limited contribution in tooth formation, they promoted the innervation of the bioengineered teeth. Using quantitative reverse transcription polymerase chain reaction and immunostainings, BMDCs were shown to promote innervation by 2 mechanisms: 1) via immunomodulation by reducing the number of T lymphocytes (CD3+, CD25+) in the implants and 2) by expressing neurotrophic factors such as NGF, BDNF, and NT3 for axonal growth. This strategy using autologous mesenchymal cells coming from bone marrow could be used to innervate bioengineered teeth without treatment with an immunosuppressor such as cyclosporine A (CsA), thus avoiding multiple side effects.

Prevalence and measurement of anterior loop of the mandibular canal using CBCT: A cross sectional study.

BACKGROUND: Anterior loop of the mental nerve is a very important anatomic landmark in implant placement and anterior mandibular osteotomies. PURPOSE: Two-dimensional imaging techniques are not competent enough to locate and measure the mental nerve loop in majority of the cases. Any injury to this loop results in pain/paresthesia/numbness in the region supplied by the mental nerve. The aim of this study is to analyze the prevalence and measure the length of the loop using cone beam computerized tomography (CBCT) and calculate the average length and prevalence so that a safe margin can be given while placing the implants or the osteotomy cuts in the premolar region. MATERIALS AND METHODS: A cross-sectional study was done using CBCT images of 85 patients taken for impaction surgery. The length of the loop was measured in mm using standardized lines drawn along specific anatomic landmarks. RESULTS: In our study 11.76% of patients had anterior loop in their mental nerve. Mean length of the mental nerve loop was calculated and found to be 2.79 mm. CONCLUSION: A margin of 4 mm anterior to the mental foramen should be safe to avoid any damage to the mental nerve loop bundle in majority of the cases where the loop is present.

Computer-guided chin harvest: A novel approach for autogenous block harvest from the mandibular symphesis.

BACKGROUND: The introduction of CAD/CAM technology allowed clinicians to carry out complex procedures with a high level of precision and reproducibility and minimize the risk of injury during the procedure. PURPOSE: The aim of the present study is to evaluate the efficacy of the CAD/CAM surgical guide during chin harvesting procedures in reducing the risk of neurosensory damage and patient morbidity compared with the standard technique. MATERIALS AND METHODS: About 20 cases of autogenous block chin harvest were randomly into two groups. The first group received computer-guided chin block harvest while the second group received autogenous block chin harvest using the standard approach. RESULTS: In the guided group, out of the 10 subjects, 2 subjects presented with wound dehiscence which resolved within 1 month. No teeth showed any negative pulp sensitivity results. The pointed-Blunt test and 2 point discrimination tests showed a single case of neurodeficits at 1 week follow-up appointment which resolved within 1 month. In the nonguided group, out of the 10 subjects, 1 case presented with wound dehiscence that resolved completely within 1 month. Pulp vitality test showed negative results in 29.4% of the involved teeth at 1 week which decreased to 9.8% and 3.9% at 1 and 6 months follow-up, respectively. The pointed blunt test revealed 3 subjects with neurodeficits at 1 week, out of which 2 subjects showed persisting symptoms at 6 months follow-up. The 2 point discrimination test showed 3 subjects with neurodeficits, out of which two subjects showed persistent symptoms with no resolution at the 6 months follow-up. CONCLUSION: Within the limits of this study, computer-guided chin harvest shows promising results in the reduction of neurosensory complications following harvesting procedures and presents as a safe alternative to the standard technique.

Cleft lip and palate: recommendations for dental anesthetic procedure based on anatomic evidences.

Patients with cleft lip and palate usually present dental anomalies of number, shape, structure and position in the cleft area and the general dentist is frequently asked to restore or extract those teeth. Considering that several anatomic variations are expected in teeth adjacent to cleft areas and that knowledge of these variations by general dentists is required for optimal treatment, the objectives of this paper are: 1) to describe changes in the innervation pattern of anterior teeth and soft tissue caused by the presence of a cleft, 2) to describe a local anesthetic procedure in unilateral and bilateral clefts, and 3) to provide recommendations to improve anesthetic procedures in patients with cleft lip and palate. The cases of 2 patients are presented: one with complete unilateral cleft lip and palate, and the other with complete bilateral cleft lip and palate. The patients underwent local anesthesia in the cleft area in order to extract teeth with poor bone support. The modified anesthetic procedure, respecting the altered course of nerves in the cleft maxilla and soft tissue alterations at the cleft site, was accomplished successfully and the tooth extraction was performed with no pain to the patients. General dentists should be aware of the anatomic variations in nerve courses in the cleft area to offer high quality treatment to patients with cleft lip and palate.

Cleft lip and palate: recommendations for dental anesthetic procedure based on anatomic evidences

Patients with cleft lip and palate usually present dental anomalies of number, shape, structure and position in the cleft area and the general dentist is frequently asked to restore or extract those teeth. Considering that several anatomic variations are expected in teeth adjacent to cleft areas and that knowledge of these variations by general dentists is required for optimal treatment, the objectives of this paper are: 1) to describe changes in the innervation pattern of anterior teeth and soft tissue caused by the presence of a cleft, 2) to describe a local anesthetic procedure in unilateral and bilateral clefts, and 3) to provide recommendations to improve anesthetic procedures in patients with cleft lip and palate. The cases of 2 patients are presented: one with complete unilateral cleft lip and palate, and the other with complete bilateral cleft lip and palate. The patients underwent local anesthesia in the cleft area in order to extract teeth with poor bone support. The modified anesthetic procedure, respecting the altered course of nerves in the cleft maxilla and soft tissue alterations at the cleft site, was accomplished successfully and the tooth extraction was performed with no pain to the patients. General dentists should be aware of the anatomic variations in nerve courses in the cleft area to offer high quality treatment to patients with cleft lip and palate.

Trigeminal neuralgia: a retrospective study of 188 Thai cases.

OBJECTIVE: To describe the clinical characteristics and treatment of trigeminal neuralgia (TN) in a group of Thai patients. MATERIALS AND METHODS: Records of 188 patients with TN were reviewed retrospectively for patient demographics, the characteristics of the pain and treatment modalities. RESULTS: Of the 188 patients, 37.2% were men and 62.8% were women. The peak incidence (46.8%) was in the age range of 50-69 years. Pain occurred on the right side of the face more often than on the left (1.8:1). The mandibular division of the trigeminal nerve was the most frequently affected (30.3%), followed by the combined maxillary and mandibular divisions (29.3%) and the maxillary division alone (25%). The majority described their attack as a sharp pain (77.6%), and the most common primary locations were at previous extraction sites (40.5%). The most common triggers were chewing (61.2%) and speaking (47.3%). Carbamazepine was the most common prescribed drug (76.1%) for the initial treatment. Combination drug therapy was introduced when the monotherapy failed to control the pain. Surgical intervention was the alternative choice of treatment in refractory cases. CONCLUSION: TN affected women more than men, and this disorder occurred most frequently in patients aged 50 years and older. The mandibular division of the trigeminal nerve was most commonly involved.

Evaluation of sensitivity of teeth after mandibular fractures.

The sensitivity of teeth anterior to a fracture between the mental and mandibular foramina has been tested and followed up until reinnervation or 3 years has passed. This study assessed the reinnervation period, the number of denervated teeth, and their clinical importance. Fifty patients and 459 teeth were examined. Two hundred and seventy-three teeth were affected and had potentially impaired innervation. Tests after injury showed non-responsive teeth in 81% of affected teeth. Six weeks after injury, 19% of teeth were reinnervated; by 1 year after injury, 92% of initially non-responsive teeth were reinnervated. Most teeth (34%) were reinnervated from 6 weeks to 3 months. All 23/186 initially non-responsive, unaffected, contralateral corresponding teeth were reinnervated within 6 weeks. A year after injury, 95% of incisors, 91% of canines, 94% of premolars, and 82% of molars were reinnervated. Three years after injury, 8% of teeth remain denervated. During the second and third years, no reinnervation occurred, but clinical signs of pulp devitalisation of denervated teeth occurred in 18% or 1% of the initially non-responsive affected teeth. The results revealed the stability of pulp 1 year after injury. Denervated teeth should not be treated if no clinical or radiological signs of devitalisation exist.

Somatosensory profiles in subgroups of patients with myogenic temporomandibular disorders and Fibromyalgia Syndrome.

Some patients with myofascial pain from temporomandibular disorders (TMD) report pain in extra-trigeminal body regions. Our aim was to distinguish TMD as regional musculoskeletal pain syndrome (n=23) from a widespread pain syndrome (FMS; n=18) based on patients' tender point scores, pain drawings and quantitative sensory testing (QST) profiles. Referenced to 18 age- and gender-matched healthy subjects significant group differences for cold, pressure and pinprick pain thresholds, suprathreshold pinprick sensitivity and mechanical detection thresholds were found. Pain sensitivity in TMD patients ranged between those of FMS patients and healthy controls. The group of TMD patients was inhomogeneous with respect to their tender point count with an insensitive group (n=12) resembling healthy controls and a sensitive TMD group (n=9) resembling FMS patients. Nevertheless sensitive TMD patients did not fulfil diagnostic criteria for FMS in regard to widespread pain as shown by their pain drawings. TMD subgroups did not differ with respect to psychological parameters. The sensitive subgroup was more sensitive compared to healthy controls and to insensitive TMD patients in regard to their QST profile over all test areas as well as to their tenderness over orofacial muscles and trigeminal foramina. However, sensitive TMD patients had a short pain duration arguing against a transition from TMD to FMS over time. Data rather suggest an overlap in pathophysiology with FMS, e.g. a disturbance of central pain processing, in this subgroup of TMD patients. Those patients could be identified on the basis of their tender point count as an easy practicable screening tool.

El nervio milohioideo en la inervación accesoria de los dientes inferiores / The milohioideo nerve in the accessory innervation of the inferior teeth

El nervio alveolar inferior (NAI) es responsable de la sensibilidad de la pulpa dentaria, papilas interdentales, periodonto, tejido óseo vecino a los dientes y, a través de las fibras que constituyen el nervio milohioideo (NM), de la inervación de los músculos milohioideo y vientre anterior del músculo digástrico. Sin embargo, hay polémica en cuanto a la participación del NM en la sensibilidad accesoria de los dientes inferiores. Nuestro objetivo fue estudiar la posibilidad de la participación del NM en la inervación accesoria de los dientes mandibulares. Estudiamos la anatomía de los NAI y NM, a través de la disección de las caras mediales de 12 mandíbulas de cadáveres adultos humanos. Identificados los NAI y NM realizamos la morfometría: A= distancia entre el origen del NM y el foramen mandibular; B= ancho del NAI antes de emitir elNM y C= ancho del NM; en milímetros. Los resultados presentaron los valores medios: A= 10,02 (+/- 4,14); B= 5, 67 (+/- 0,97); C= 2,95 (+/- 0,437). La medida A fue la que más osciló; las mandíbulas 8 y 11 presentaron pequeños ramos del NM penetrando en la cara medial del hueso. La variación de la medida A puede justificar la no inclusión del NM en una anestesia del NAI. Las medidas B y C ilustran aspectos topográficos de los nervios NAI y NM que pueden ser aplicados a la práctica odontológica. Los hallazgos de ramos nerviosos penetrando en la mandíbula, tienen correspondientes en la literatura. Este estudio, enfocando la morfometría de los NM y NAI y las relaciones entre NM y NAI, puede posibilitar hipótesis diagnósticas relativas a la inervación accesoria de los dientes inferiores.

The inferior alveolar nerve (IAN) is responsible to innervation for the dental pulp, papillae interdentals, periodontal, bone tissue neighbour to the teeth and through the nerve fibers of the Mylohyoid Nerve (MN) by innervation mylohyoid muscle and anterior belly of the digastric muscle. However there is controversy about the involvement of MN in auxiliary sensitiveness of the teeth downwards. Our objective is to study the possibility of involvement of MN in accessory innervation of mandibular teeth. Studie the anatomy of the IAN and MN through the dissection of the medial side of 12 mandibles of adult human cadavers. IAN and MN identified so perform the morphometry: A – distance between the origin of MN and mandibular foramen; B – width of the NAI before issuing the MN; C – width of MN; in millimeters. The results provide the average values: A= 10.02 +/- 4.14; B = 5.67 +/- 0.97; C = 2.95 +/- 0.437. Measure A was the most varied; the mandibles 8 and 11 showed smal branches of MN in penetrating the medial side of the bone. The change of measure A can to justify the not inclusion of MN in the anesthesia of IAN. Measures B and C illustrate aspects of topographical of MN and IAN nerves that can be applied to the dental practice. The findings of branchs of the MN penetracting in mandible has correspondents in the literature. This study focusing on the morphometry of the IAN and MN and relations between them can enable diagnostic hypotheses concerning accessory innervation of lower teeth.

Local differences in the position of the mental foramen.

The mental foramen has been reported to vary in position in different ethnic groups. Repeated failures during injections and operative procedures involving the mental foramen suggest the presence of local differences in a given population. The aim of the present study was to investigate possible local differences of the mental foramen in Eastern Anatolian individuals in the Turkish population. The present investigation is based on the examination of 70 adult mandibles. The study consisted of three measurements, to include the relations of the mental foramen to the following: 1) the lower teeth; 2) the body of mandible; 3) the mandibular symphysis and posterior border of the ramus of the mandible. The most common position of the foramen was in line with the longitudinal axis of the second premolar tooth (relation IV), at the midpoint of the mandibular body height and at 1/3.5 of the distance from the mandibular symphysis to the posterior border of the ramus. Local differences of the mental foramen may occur in a population. Prior to surgery knowledge of the most common location of the foramen peculiar to a local population may enable effective mental block anaesthesia to be provided.

Branching patterns and intraosseous course of the mental nerve.

PURPOSE: The purpose of this study was to clarify the branching patterns of the mental nerve (MN) and intraosseous courses of the MN branches, and to determine the clinical relevance of the various courses of the MN branches. MATERIALS AND METHODS: We investigated the topography of the MN by dissecting 31 hemifaces of Korean cadavers. Based on the distribution area of the MN, it was divided into angular (A), medial inferior labial (ILm), lateral inferior labial (ILl), and mental (M) branches. We classified the branching patterns of the 4 branches of the MN into 5 types. RESULTS: Type II, in which the MN divided into 3 branches (A, ILm, and M), with the ILl branch separating from the A branch, was the most common (35.4%). The MN was classified based on the shape of the anterior loop into loop, straight, and vertical patterns, which constituted 61.5%, 23.1%, and 15.4%, respectively. In the mandibular canal, the inferior alveolar nerve completely divided into the MN and the dental nerve, which supplies the teeth. In 17 cases (81%), the nerve bundles constituting the A branch were located at the superior aspect, whereas the nerve bundles of the inferior labial and mental branches were in the middle and inferior aspects within the mandibular canal, respectively, at the mental foramen region. CONCLUSION: These observations can help clinicians to predict the location or extent of paresthesia in the facial region according to the location and extent of nerve damage during dental implant surgery or genioplasty.

Taste deficits related to dental deafferentation: an electrogustometric study in humans.

Dental treatments, the prevalence of which increases with age, can cause orofacial somatosensory deficits. In order to examine whether they may also affect taste sensitivity, electrogustometric thresholds were measured at 9 loci on the tongue surface in 391 healthy non-smoking, non-medicated subjects. Results showed that the greater the number of deafferented teeth, the higher the thresholds. Irrespective of age, subjects with more than 7 deafferented teeth exhibited significantly higher thresholds than subjects with fewer than 7 deafferented teeth. Conversely, across age groups, no statistical difference was observed among subjects with no, or few, deafferented teeth. Hence, a taste deficit, which was not correlated to aging, was observed. An association was noticed between the location of taste deficits and the location of deafferented teeth. Higher thresholds at anterior sites, with no possible traumatic injury relationship, suggested that neurophysiological convergence between dental somatosensory and taste pathways - possibly in the nucleus tractus solitarius - could be responsible for these relative decreases of taste sensitivity when dental afferences were lacking. Among trigeminal contributions, lingual nerve and inferior alveolar nerve may synergize taste.

Proposal for a standardized protocol for the systematic orofacial examination of patients with Hereditary Sensory Radicular Neuropathy.

AIM: To apply a standardized protocol for the orofacial evaluation of two adult siblings (one male and one female) with Hereditary Sensory Radicular Neuropathy (HSRN) that presented with dental problems. SUMMARY: The systematic evaluation consisted of (a) clinical questionnaire; (b) radiographs [orthopantomography and computarized tomography (CT)]; (c) orofacial psychophysical tests (pain, thermal, mechanical and electrical sensation); and (d) histology of gingiva and pulp (optical and transmission electronic microscopy). The female patient had complete insensitivity to orofacial pain and partial facial heat sensitivity, and received dental treatment without anaesthesia or pain. She had a severe and painless jaw infection due to pulp necrosis in tooth 37. The male patient had partial insensitivity to orofacial pain and required anaesthesia for dental treatment. Histological examination of gingivae and pulpal tissue revealed an altered proportion of unmyelinated and myelinated sensory nerve fibres. KEY LEARNING POINTS: * Patients with HSRN may present with significant, silent dental disease. * A standard protocol is helpful when evaluating such patients. * If the opportunity arises, evaluation of pulp tissue may reveal an altered proportion of myelinated and unmyelinated nerve fibres. This may avoid the more estabilished sural nerve biopsy.

The mental foramen and nerve: clinical and anatomical factors related to dental implant placement: a literature review.

BACKGROUND: The mental foramen is a strategically important landmark during osteotomy procedures. Its location and the possibility that an anterior loop of the mental nerve may be present mesial to the mental foramen needs to be considered before implant surgery to avoid mental nerve injury. METHODS: Articles that addressed the position, number, and size of the mental foramen, mental nerve anatomy, and consequences of nerve damage were evaluated for information pertinent to clinicians performing implant dentistry. RESULTS: The mental foramen may be oval or round and is usually located apical to the second mandibular premolar or between apices of the premolars. However, its location can vary from the mandibular canine to the first molar. The foramen may not appear on conventional radiographs, and linear measurements need to be adjusted to account for radiographic distortion. Computerized tomography (CT) scans are more accurate for detecting the mental foramen than conventional radiographs. There are discrepancies between studies regarding the prevalence and length of the loop of the mental nerve mesial to the mental foramen. Furthermore, investigations that compared radiographic and cadaveric dissection data with respect to identifying the anterior loop reported that radiographic assessments result in a high percentage of false-positive and -negatives findings. Sensory dysfunction due to nerve damage in the foraminal area can occur if the inferior alveolar or mental nerve is damaged during preparation of an osteotomy. CONCLUSIONS: To avoid nerve injury during surgery in the foraminal area, guidelines were developed based on the literature with respect to verifying the position of the mental foramen and validating the presence of an anterior loop of the mental nerve. These guidelines included leaving a 2 mm zone of safety between an implant and the coronal aspect of the nerve; observation of the inferior alveolar nerve and mental foramen on panoramic and periapical films prior to implant placement; use of CT scans when these techniques do not provide clarity with respect to the position of the nerve; surgical corroboration of the mental foramen's position when an anterior loop of the mental foramen is suspected of being present or if it is unclear how much bone is present coronal to the foramen to establish a zone of safety (in millimeters) for implant placement; once a safety zone is identified, implants can be placed anterior to, posterior to, or above the mental foramen; and prior to placing an implant anterior to the mental foramen that is deeper than the safety zone, the foramen must be probed to exclude the possibility that an anterior loop is present. In general, altered lip sensations are preventable if the mental foramen is located and this knowledge is employed when performing surgical procedures in the foraminal area.

Predictive factors in infraorbital sensitivity disturbances following zygomaticomaxillary fractures.

The aim of this study was to define if the alterations in sensory modalities could be a predictive factor in the prognostic recovery of the ION. Ten patients that had suffered facial trauma, associated with sensitivity alterations of the ION were evaluated prospectively. Touch detection thresholds (TD) were measured using Von Frey's filaments aesthesiometer. A warm/cold discrimination (W/C) was also done to the patients, on the same areas. The patients were examined in both sides of the face, using the non-traumatized side as control. The tests were done before surgery and several times postoperatively. For statistical analysis of the results, the two-sample t test was used. A significant difference (P < 0.0001) in the mean tactile recovery time between the areas without thermal sensitivity before surgery and those with normal thermal sensitivity before surgery was observed. Therefore, we propose that during the preoperative examination, the surgeon examines the thermal discrimination in order to establish prognosis and approximate recovery times.

Effects of 50 Hz electromagnetic fields on electroencephalographic alpha activity, dental pain threshold and cardiovascular parameters in humans.

Recent studies indicate that exposure to extremely low frequency magnetic fields (ELF MFs) influences human electroencephalographic (EEG) alpha activity and pain perception. In the present study we analyse the effect on electrical EEG activity in the alpha band (8-13 Hz) and on nociception in 40 healthy male volunteers after 90-min exposure of the head to 50 Hz ELF MFs at a flux density of 40 or 80 microT in a double-blind randomized sham-controlled study. Since cardiovascular regulation is functionally related to pain modulation, we also measured blood pressure (BP) and heart rate (HR) during treatment. Alpha activity after 80 microT magnetic treatment almost doubled compared to sham treatment. Pain threshold after 40 microT magnetic treatment was significantly lower than after sham treatment. No effects were found for BP and HR. We suggest that these results may be explained by a modulation of sensory gating processes through the opioidergic system, that in turn is influenced by magnetic exposure.

Coordination of trigeminal axon navigation and patterning with tooth organ formation: epithelial-mesenchymal interactions, and epithelial Wnt4 and Tgfbeta1 regulate semaphorin 3a expression in the dental mesenchyme.

During development, trigeminal nerve fibers navigate and establish their axonal projections to the developing tooth in a highly spatiotemporally controlled manner. By analyzing Sema3a and its receptor Npn1 knockout mouse embryos, we found that Sema3a regulates dental trigeminal axon navigation and patterning, as well as the timing of the first mandibular molar innervation, and that the effects of Sema3a appear to be mediated by Npn1 present in the axons. By performing tissue recombinant experiments and analyzing the effects of signaling molecules, we found that early oral and dental epithelia, which instruct tooth formation, and epithelial Wnt4 induce Sema3a expression in the presumptive dental mesenchyme before the arrival of the first dental nerve fibers. Later, at the bud stage, epithelial Wnt4 and Tgfbeta1 regulate Sema3a expression in the dental mesenchyme. In addition, Wnt4 stimulates mesenchymal expression of Msx1 transcription factor, which is essential for tooth formation, and Tgfbeta1 proliferation of the dental mesenchymal cells. Thus, epithelial-mesenchymal interactions control Sema3a expression and may coordinate axon navigation and patterning with tooth formation. Moreover, our results suggest that the odontogenic epithelium possesses the instructive information to control the formation of tooth nerve supply.

Clinical and anatomy study of the human mental foramen.

The great diffusion of the surgical techniques in jaws surgery and the progress of the radiological imagining procedures expressed many interest in clinical anatomy of the mental foramen (MF). The study goal was to determine the precise location of the MF and the surrounding anatomical landmarks. Measurements of the MF position relative to the surgical landmarks and related posterior teeth were made on 20 dry mandibles with complete dentition and intact alveolar bridge obtained from the Institute of Anatomy, School of Medicine, University in Sarajevo. The measurements were made by anthropometric methods on the booth sides of the mandible, and compared with measurement made on the orthopantomogram radiographs of the same mandibles. The most common position of the MF was in line with the longitudinal axis of the second premolar. In the vertical plane on the skulls the MF lays in the midpoint of the distance between the lower border of the mandible and the alveolar margin, however on the orthopantomogram MF appeared slightly bellow the midpoint. In the horizontal plane it lays approximately one third of the distance between the mandibular symphysis and the posterior border of the ramus of the mandible measurement from A-P projection and one quarter of that distance measurement from the profile projection. There were no significant differences between distances MF from posterior border of the ramus of the mandible measurement from A-P and profile projection and the one obtained on orthopantomogram and their ratio is constant value determine das 1,065. The MF was on average 25 mm lateral to the mandibular skeletal midline and symmetrical, and symmetry was preserved on the orthopantomogram. The measurement showed significant differences in distances of M from superior border mandible measurement on dry mandible and orthopantomogram radiographs while distance bellow the MF was not significantly different. The constant values of MF distance to the posterior border of the ramus of the mandible measured as 1,065 and the distance to the medial skeletal line of 2,11 made it possible to also determine average angle of 43 degrees stream of the cor-pus of the mandible behind MF. These values in combination with ratios of MF to the different anatomic landmarks designated as relative horizontal and relative vertical position, would be of importance not only from anatomical but also from practical point of view for estimation of alveolar bridge resorption and preoperative analysis in orthognat postresection or implant surgery in the mandible.